Fluid pressure servo-motor for tilting propeller blades



A. PFAU March 14, 1933.

FLUID PRESSURE SERVO MOTOR FOR TIL'I'ING PROPELLER BLADES Filed July 23, 1951 .2 Sheets-Sheet 1 Millllli A. PFAU March 14, I933.

FLUID PRESSURE SERVO MOTOR FOR TILTING PROPELLER BLADES 2 Shets-Sheet 2 Filed July 23, 1931 t. u m-agg I II Patented Mar. 14, 1933 UNITED STATES PATENT OFFICE ARNOLD PFAU, OF MILWAUKEE, WISCONSIN, ASSIGHOR TO ALLIS-CHALMERS MANU- FACTURING GOMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF DELL- WARE FLUID PRESSURE SERVO-MOTOR FOR TILTTNG PROPELLER BLADES Application filed July 83,

This invention relates in general to fluid pressure operated motors, and more in particular to servo-motors for tilting the rotor blades of hydraulic turbines, pumps, marine and aircraft propellers, and the like.

It is known that the eiiiciency of hydraulic turbines of the propeller type can be increased when operating with low loads and low effective heads of water by tilting the propeller blades. Various mechanism in the propeller hub for tilting the propeller blades by means of rods which are movable longitudinally of the propeller shaft have been devised, noting, for example, the mechanism shown in the patent to V. Kaplan, 1,467,672, issued September 11, 1923. t is desirable to mount the servo-motor which operates the blade tilting rod co-axial of the turbine shaft so as to dispense with the use of massive levers and to avoid the unsymmetric appearance of exposed parts.

An object of this invention is to provide a propeller blade tilting servo-motor having a piston with different effective areas on the oppositefsides thereof.

Another object of this invention is to provide a servo-motor. adapted to be connected at one end or intermediate the ends of a rotatable propeller shaft for rotation therewith and adapted to operate a rod relative to the shaft.

Another, object of this invention is to rovide a servo-motor in'which operating Enid is conducted from a stationary conduit to a rotatable piston chamber.

A further object of this invention is to operate the blade tilting rod of a propeller type; turbine by means of a servo-motor comprising a constant pressure chamber and a variable pressure chamber.

These and other objects and advantages are attained by this invention, various novel features of which will be apparent from the description and drawings herein, and will be more particularly pointed out in the claims.

Various illustrative examples of the application of this invention are shown in the accompanying drawings, in which:

Figure 1 shows a system for controlling 1981. Serial No. 552,840.

the tilt of the runner blades of a hydraulic turbine;

Fig. 2 is a vertical section of a stationary servo-motor embodying the present invention;

Fig. 3 is a vertical section of a rotatable servo-motor embodying the present invention;

Fig. 4 is a vertical section of a servo-motor adapted to be interposed intermediate the ends of a turbine shaft;

Fig. 5 is a horizontal sectional view of Fig. 4, taken on line V-V;

Fig. 6 is a side elevation of a portion of the servo-motor shown in Fig. 4 with the casing broken away.

Fi 7 is a horizontal, sectional view showing t e arrangement of valve ports and fluid conduits, and is taken on line VII-VII of Fig. 4.

Fig. 8 is a vertical sectional view of the valve gear shown in Fig. 4 taken on line VIII-VIII of Figure 7.

Fig. 9 is a side view of a portion of a turbo-generator installation having a servomotor similar to that shown in Fig. 4.

With the above objects in view, as well as other objects which will appear as the specification proceeds, the invention comprises the construction, arran ement, and combination of parts now to full described and hereinafter claimed: It ing understood that the disclosure herein described is merely illustrative of the invention and is not to be taken in a limited sense, change in detail of construction and arrangement of parts being permissible so long as within the spirit of the invention and the scope of the claims which follow:

Referring now to Figure 1, 10 is a h draulic turbine havin adjustable i e vanes 11, and a rotor ub member 2 to which tiltable blades 13 are connected. Any suitable mechanism within hub 12 for tilting blades 13 may be used noting the patent to J. J. Ring, U. 5. 1,685,756, September 25, 1928, for a typical showing of such mechanism. A servo-motor 16 is connected to guide vanes 11 by means of linkage 15 and is controlled by governor 18 which actuates end to a piston 38 b servo-motor valve 17. The motion of guide vanes 11 is relayed to topographic cam device by means of linkage 15, lever 19 and arm 21. A runner blade tilting servo-motor 30 has its valve 56 controlled b means of a topographic cam device 20 t rough the medium of hell crank 29, link 28, and cam follower 27. The topo raphic cam device 20 is transversely move by motor 22 which is operative in response to the difference between the height of float 25 in the headwater and float 26 in the tail-water by means of a differential transmitter device 24 and a follow up receiver device 23. Servo-motor 30 is mounted directly on the casing of generator 31 and has a rotor blade tilting rod (noting Fig. 2) extending longitudinally through hollow shaft 32.

No claim is made herein to the above described hydraulic turbine control system comprising governor controlled guide vanes, a servo-motor for tilting the runner blades, a topographic cam device for controlling the blade tiltin servo-motor in accordance with both the e ective head of water and the position of the guide vanes, which system constitutes the subject of a copending application, Serial No. 552,639 filed by this same inventor on July 23, 1931.

Referring now to Fig. 2, servo-motor cylinder 33 is provided with a base portion 44 for connection to the generator frame in which guide bearing 46 for shaft 32 is located. Cylinder 33 also has an upper cylinder head member 34 with axial bore 35 therein and a lower cylinder head portion 36 having an axial bore 37 therein. A piston 38 is slidable within c linder 33 and has a sleeve portion 39 exten ing through the bore 37. A piston rod 40, which is attached at its lower end to any suitable runner blade tilting mechanism, is attached at its upper bearing comprising ba 1 rings 41 and 43 and collar 42. Piston 38, cylinder 33, head portion 36 and sleeve portion 39, define a chamber which is constantly supplied with fluid under ressure from inlet pipe 49. The face 47 of piston 38 represents the effective area acted on b the operating fluid under pressure in c amber 50. C linder head 34, cylinder 33, piston 38, an valve member 54, definea chamber 53 which obtains oil under variable ressure from chamber 50 by means of ori ces 51 and 52. The diameter of orifice 51 is smaller'than the diameter of orifice 52 and serves to reduce the pressure of the oil flowing therethrough. Valve member 54 is attached to the upper face of piston 38 and is slidable through bore 35 in cylinder head 34 and is provided with a assageway 55 which permits fluid to flow rom chamber 53 to chamber 58. A valve needle 56 is slidable through a portion of cylinder head 34 into engagement means of a thrust.

with the seat surface of valve 54, and serves to control the flow of fluid from chamber 53 through passageway 55 into drain chamber 58. From dramchamber 58 the fluid is free to flow through drain conduit 59 into drain chamber 60 and out drain pipe 61. Valve needle 56 is controlled by the topographic cam device 20, described In connection with Figure 1, by means of link 57, rod 28 and, bell crank 29, which is pivoted on arm 62.

The operation of Fig. 2 is as follows: With valve needle 56, in the normal static osition shown, oil under pressure from inlet pipe 49. flows into chamber 50 and through orifice 51 which throttles down the pressure of the oil, around the thrust bearing, through large orifice 52 into variable pressure chamber 53, through passageway 55, past valve needle 56 into drain chamber 58 and out through drain conduit 59 and drain pipe 61. chamber 50 acts against piston face 47 tending to move the piston upward, but the oil under lower pressure in chamber 53 acts against piston face 48 which has a greater area than face 47 and the piston consequently remains stationary. Upon occurrence of a downward movement of valve needle 56, the flow of oil through passageway 55 will be reduced and the pressure of the oil in chamber 53 will therefore increase and piston 38 will be forced downwardly. The downward movement of piston 38 moves valve member 54 away-from valve needle 56 and ultimately decreases the pressure in chamber 53 to such a value that the forces acting on the piston 38 again become balanced. Upon occurrence of an upward movement of valve needle 56, the flow of oil through passageway 55 is increased and the pressure in chamber 53 is consequently reduced, thereby causing the oil under constant pressure in chamber 50 to move the piston 38 upwardly until the forces on the piston become balanced again. It is thus seen that the piston 38 follows u the movement of the valve needle 56. he flow of oil from chamber 50 to chamber 53 serves to lubricate the thrust bearing which connects shaft 40 to piston'38.

Referring now to Fig. 3, the servo-motor shown in this figure is substantially the same as that shown in Fig. 2, except that. the cylinder member 33 is attached by suitable means to rotatable turbine shaft 32 instead of mounted upon the stationar generator frame. This construction 0 viates the necessity of a thrust bearing for the turbine blade tilting rod 40, but does require means for transferring fluid under pressure from the stationary member to the rotatable servo-motor cylinder. A housing member 63 is mounted on generator frame 45 and has an arm 62 for carrying the bell crank 29 and a guide member for the valve needle 56,

The high oil pressure in similar to the construction shown in Fig. 2. The rotatable cylinder 33 is providedwith an annular groove into which a twoart annular slip ring 64 is free to slide. This slip ring member 64 is provided with an annular groove 65 therein and is prevented from rotating with cylinder 38 by means of a stop member 67 attached to housing 63. Fluid under ressure is conducted from a source of flui pressure through inlet pipe 49', which is attached to slip ring 64, into oove 65 and through inlet bores 66 and 66' into the constant pressure chamber 50. A single orifice 51' connects chamber with chamber 53. A leakage drain chamber 70 having outlet 69 is provided in cylinder member 33 to collect any possible fluid which may leak past head portion 36 and sleeve member 39 in bore 37.

The 0 eration of F' 3 is as follows:

Consi er that the position of valve needle 56 is that which corresponds to the normal static position of piston 76. Fluid under pressure flows through conduit 49', into groove 65, through inlet bores 66 and 66', into constant pressure chamber 50 and acts against an efiective area of the piston face represented by reference number 47. From chamber 50, fluid flows through orifice 51' into variable pressure chamber 53, through passageway 55 and along the walls of linder 33 into drain chamber and out rain pipe 61. The pressure in chamber 53 is less than the pressure in chamber 50 due to the throttling action of orifice 51', but inasmuch as the efiective area of face 48 is greater than the eflective area 47, the pressure on the two sides of the piston are balanced and the piston therefore remains stationary. Upon movement of the valve needle 56, the changes of the difierential pressure in chambers 50 and 53 are the same as described in connection with Fig. 2.

Referring now to Figs. 4, 5, 6 7 and 8, the shaft between the turbine and the generator is constructed in two sections 32 and 32' having flange members 74 and 71, re- ?ipectively, which enga e corresponding ange members 73 and 2 of servo-motor cylinder 33. A stationary housin member 75 surrounds the servo-motor cy inder 33 and is supported from any suitable stationary structure such as the enerator foundation or the upper part of t e turbine easing. An inner cylinder member 33 is mounted within member 33, however, a si le cylinder member obviously could be used. A piston 76 is slidable within cylinder member 33' and is provided with sleeve member 77 which is slidable in bores 37' and 37 of the cylinder head portion.

Fluid under pressure is supplied to the servo-motor by means of pressure inlet conduit 49', which is attached to slip ring 64, which in turn is slidable in groove ot cylinder 33. Fluid in groove 65' is in communication with constant pressure chamber 50 through inlet bores 66 and 66'. Piston 76 is provided with an axial bore in which valve 82 is free to slide, and is also provided with fluid assageways 78, 79, 80, and 81, the inner en s of which constitute ports controlled by valve 82. Fi 7 and 8 show more in detail the disposition of these passageways around the valvemember 82. Constant ressure chamber 50 is in communicationwith the reduced portion of valve 82 by means of port 81. The upper face 48 of piston 76, cylinder 33, c hnder head 68, and valve 82 define a van ab e pressure chamber 53. This chamber 53) is in communication with the constant pressure chamber 50 by means of passageway 80 when valve 82 is moved downwardly. Head members 92 and 93, cylinder 33' and sleeve member 77 define a drain chamber 91. When valve 82 is moved upwardly, variable ressure chamber 53 is in communication wit the atmosphere by means of pasageway 69, passageway 78, drain chamber 91, rotatable drain outlet 69, lower drain chamber 60 and drain pipe 61'.

Refering more in particular to Figs. 4 and 5, valve 82 is attached to spider member 84 by means of nut 83. S ider shoes 85 are attached to the outer en s of spider 84 by means of nuts 86. The spider shoes 85 are slidably sup orted by an annular thrust ring 87 whic turn is supported by a yoke member 88 hich is pivota 1y attached to the thrust ring. operating arm 90, integral with yoke 88, is pivoted to the housing member by means of pivot 89. 'Arm 90 is moved in accordance with the altitude of topographic cam member 20 by means of any suitable linkage.

The operation of the device shown in Figs. 4, 5, 6, 7 and 8, is as follows:

With valve 82 in the normal inactive p:- sition shown, the fluid pressure in cham r 50 actin a ainst piston area 47 is balanced by the ui pressure in chamber 53 actin upon the greater area 48. Upon an upwar movement of yoke operating arm 90, annular thrust ring 87 moves downwardly thereby causing valve 82 to move downwardly. A downward movement of valve 82 to a position lower than that shown in Fig. 4, causes fluid to flow from constant pressure chamber 50 through pasageway to variable pressure chamber 53, to increase the fluid pressure therein. The increase of fluid pressure in chamber 53 causes piston 76 to move downwardly relative to the valve 82 thereby ultimately closing passageway 80. Conversely upon an upward movement of valve 82, the lower end of this valve opens the rt in passageway 79 and permits the flui under pressure in chamber 53 to flow through passageway 79 and passageway 78 into drain chamber 91 and out through drain pipes 69 and 61'. This action causes the ressure in cylinder 53 to reduce and resu ts in the pressure in chamber 50 moving piston 76 upwardly until the motion of the piston relative to valve 82 closes passagewa 79 and 78. and entra suflicient fluid in chamber 53 to balance t e ressure of the fluid in chamber 50. It is t us seen that piston 76 is caused to follow the movement of valve 82 and that as the piston 76 approaches each static ition tie ports uncovered by valve 82 will graduall close causin the fluid in chamber 53 to t rottle throug the restricted valve-openings in substantially the same manner that fluid throttles through the orifices shown in Figs. 2 and 3. It is to be understood that t e type of Vilma! shown in Fig. 2 and 3,

can also be in a rotary servo-motor of the type shown in 4.

Fig. 9 shows a modified form of the valve gear used in the servo-motor shown in Fi s. 4, 5, 6, 7 and 8. In this modification, va ve 82', instead of being operated by a system comprising rotatable spider shoes, annular thrust ring, and a yoke member is'operated by means of a long rodwhich extends thE'O h the hollow center of generator shaft 32 nected to hell crank 29 by means of link 57 and an suitable rotatable connecting means 95. e further operation of this modification is the same as that of Figs. 4, 5, 6, 7 and 8. Obviously this type of valve gear can be used with the type of servo-motor shown in Figs. 2 and 3. i It is claimed and desired to secure by Letters Patent:

1. In combination, a rotatable shaft, a servo-motor cylinder member attached to said rotatable shaft for rotation therewith, an operatin rod eo-axial of said rotatable shaft, a piston having an orifice therethrough and dividing said cylider member into two chambers, means including a slip ring member for maintaining oil underconstant pressure in one of the chambers in said c linder members whereb oil flows throug said orifice into the ot er of said chambers, means for controlling the flow of oil from said other chamber to control the position of said piston relative to said cylinder and means comprising a stationa trough for conductng oil away from sai servo-motor. 4

2. In combination, a rotatable shaft, a cylinder member carried by said shaft and rotatable therewith, a piston having faces with different efiective areas slidable within said cylinder, a piston rod attached to said piston, means for conducting fluid under pressure to said cylinder member to continuously exert a continuous constant pressure on the face of said piston having 11 this modification, valve 82 is con the lesser elective area, a valve member for controlling the pressure of said fluid on the face of said piston having the greiiter area to therglg control the movement of said piston said valve member being rotatable with said 0 linder member, and nonrotatable means or controlling the operation of said valve member.

3. In combination, a rotatable shaft, a servo-motor cylinder member interposed between the ends of said shaft for rotation therewith, -a piston within said cylinder member, a piston rod connected to said iston stationary means for conducting uid un er pressure to and from said rotatable cylinder member, a valve rotatable with said cylinder member for controlling the position of said piston relative to said cylinder member, a valve actuating member attached to said valve, a ring member arranged in sliding contact with said valve actuating member, and means for axially moving said rin member to thereby control the movement 0 said valve member.

4. In combination, a sectional hollow shaft havin an enlarged section intermediate its an s enclosing a servo-motor cylinder, a piston within said cylinder, a piston rod connected to said piston and slidable within said hollow shaft, said piston and cylinder defining a constant pressure chamber on one side of said piston, a variable pressure chamber on the other side of said chamber, and a drain chamber, means for conducting fluid under constant pressure to said constant pressure chamber, means including a valve for selectively connecting said variable pressure chamber to either said constant pressure chamber or to said drain chamber to control the osition of said piston relative to said cy inder, and means com rising an annular thrust ri for transmitting control impulses to sai valve.

5. In combination, a stationary frame member having a bearing therein, a hollow shaft rotatable in said bearing, a stationary servo-motor cylinder carried by said stationary frame, a piston within said cylinder and having an orifice therethrough, a piston rod within said hollow shaft and rotatable therewith, a thrust bearing for connecting said rod with said piston, means for impressin oil at constant pressure on one side of sai iston, means for conducting oil from sai one side through said bearin and throu b said orifice to the other si e of said piston, and means for varying the pressure of the oil impressed on the other side of said piston to control the longitudinal movement of said piston rod. 6. In combination, a rotating shaft havmg two sections, a servo-motor having a cy nder interposed between said-sections, .a piston slidable with said cylinden'afvalve 7 1o infisan enlarged portion'intermediate its a servo-motor enclosed within said enlarged portion, a valve for controlling the operation of said servo-motor, a valve op erating member connected to said valve, a

1 stationary member arranged in close proximity to said enlarged ortion, means for carrying operatin fluid to and from said servo-motor, a for d lever member pivoted on said stationary member, an annular g0 thrust ring pivotally attached to said fork lever and m sliding contact with said valve operating member.

In testimony whereof, the signature of the inventor is afixed hereto.

as ARNOLD PFAU.

- csnrmcnsor CORRECTION.

Patent No. 1,901,772. March 14, 1933.

ARNOLD PFAU.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 4, line 64, claim 2, strike out the word "continuous"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in thePstent Oiiice.

Signed sndeealed this 16th day of May, A. D. 1933.

' Ml Jo (Seal) Acting Commissioner of Patents.

7 1o infisan enlarged portion'intermediate its a servo-motor enclosed within said enlarged portion, a valve for controlling the operation of said servo-motor, a valve op erating member connected to said valve, a

1 stationary member arranged in close proximity to said enlarged ortion, means for carrying operatin fluid to and from said servo-motor, a for d lever member pivoted on said stationary member, an annular g0 thrust ring pivotally attached to said fork lever and m sliding contact with said valve operating member.

In testimony whereof, the signature of the inventor is afixed hereto.

as ARNOLD PFAU.

- csnrmcnsor CORRECTION.

Patent No. 1,901,772. March 14, 1933.

ARNOLD PFAU.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 4, line 64, claim 2, strike out the word "continuous"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in thePstent Oiiice.

Signed sndeealed this 16th day of May, A. D. 1933.

' Ml Jo (Seal) Acting Commissioner of Patents. 

